Lemarkism

1. PRESENTED BY:
S M SHAYEZ KARIM
M.Sc. Bioinformatics
Central University of South Bihar

2. Lamarck
First theory of evolution was proposed by
Jean Baptist de Lamarck(1744-1829) .
He explained it in his famous Book
“Philosophie Zoologique” in (1809).
Lamarck held that organisms acquire
characters during their lifetime for
adapting to environment, and their
acquired character are inherited by the
offspring . By accumulation of acquired
characters over many generations, the
species is modified into a new one.

3.  Lamarck noticed that organisms adapted to a particular niche
had well developed specialised organs.
 For example a carnivore will have long canine teeth to grip its
prey

4.  Small non-functional organs
(vestigial organs) e.g. the
appendix in humans, the internal
hind limbs of whales and the
internal legs of some species of
snakes.
 Comparative anatomy showed
that these organs resembled those
which were much more
developed, with particular
functions, in other species

5.  He proposed that if an organ is used a lot it will develop and
strengthen
 If it is not used it will atrophy
 He called this the law of use and disuse

6.  Lamarck’s theory required adaptation to create new variations
 This was followed by the inheritance of these characteristics
 Darwin’s theory requires random hereditary variation first,
followed by selection of the variations
 The argument was over when Mendel’s laws of genetics were
rediscovered at the end of the 19th century
 Variations are due to hereditary traits passing from one
generation to the next in predictable frequencies

7.  Characteristics acquired during the lifetime of a parent are not
passed onto the offspring
 An athlete who develops a large muscle mass through training
does not have children who already possess this large muscle
mass
 Children of a Nobel laureate may not be as intelligent as the
parent.
 Boring of ear and nose in Indian.

8.  Behaviour can be different
 Some behaviour patterns are innate and will also evolve in by
natural selection
 learned behaviour patterns can be changed within a
generation
 Members of a social group who have acquired the behaviour
in their lifetimes will pass these learned skills onto others
including their children
 This pattern of evolution resembles the Lamarckian pattern
 The evolution of learnt behaviour is much faster than genetic
evolution and it plays an important role in human cultural
evolution

9.  Ncert biology - textbook for class 12
 Pradeep's a text book of biology for class 12